A short ppt on transmission media with its pros cons guided unguided and other sub topics explained in a brief non technical manner so that it is easy to explain and answer questions upon... enjoy

1. TRANSMISSION MEDIA
A GUIDED AND UNGUIDED APPROACH TO INTERNET…

2. TRANSMISSION MEDIUM
• A transmission medium is a material substance (solid, liquid, gas, or plasma) that can propagate energy waves.
For example, the transmission medium for sounds is usually a gas, but solids and liquids may also act as a
transmission medium for sound.
• The absence of a material medium in vacuum may also constitute a transmission medium for electromagnetic
waves such as light and radio waves. While material substance is not required for electromagnetic waves to
propagate, such waves are usually affected by the transmission media they pass through, for instance by
absorption or by reflection or refraction at the interfaces between media.
• The term transmission medium also refers to a technical device that employs the material substance to transmit
or guide waves. Thus, an optical fiber or a copper cable is a transmission medium. Not only this but also is able to
guide the transmission of networks.
• Electromagnetic radiation can be transmitted through an optical medium, such as optical fiber, or through twisted
pair wires, coaxial cable, or dielectric-slab waveguides. It may also pass through any physical material that is
transparent to the specific wavelength, such as water, air, glass, or concrete. Sound is, by definition, the vibration
of matter, so it requires a physical medium for transmission, as do other kinds of mechanical waves and heat
energy.

3. TRANSMISSION AND
TELECOMMUNICATION
• A physical medium in data communications is the transmission
path over which a signal propagates.
• Many transmission media are used as communications channel.
• For telecommunications purposes in the United States,
transmission media are classified as one of the following:
1. Wired (or guided)—waves are guided along a solid
medium such as a transmission line.
2. Wireless (or unguided)—transmission and reception are
achieved by means of an antenna.

4. CLASSES OF TRANSMISSION
MEDIA
• Wired or guided media
• Use a conductor such as a wire or a fiber optic cable to
move the signal from sender to receiver.
• Examples include telephone networks, cable television
or internet access, and fiber-optic communication.
• Wireless or unguided media
• Use radio waves of different frequencies and do not
need a wire or cable conductor to transmit signals.
• Examples of applications of radio wireless technology
include GPS units, garage door openers, wireless
computer mice, keyboards and headsets, headphones,
radio receivers, satellite television, broadcast television
and cordless telephones.

5. GUIDED OR WIRED
TRANSMISSION MEDIA
Twisted Pair Wires
• Consists of two insulated copper wires
arranged in a regular spiral pattern to
minimize the electromagnetic interference
between adjacent pairs
Coaxial Cable (or Coax)
• Used for cable television, LANs, telephony
Fiber Optic Cable
• Relatively new transmission medium used by
telephone companies in place of long-
distance trunk lines

6. TWISTED PAIR WIRES
• Consists of two insulated copper wires arranged in a regular spiral pattern to minimize the
electromagnetic interference between adjacent pairs
• Often used at customer facilities and also over distances to carry voice as well as data
communications
• Low frequency transmission medium
• Types of Twisted Pair:
• STP (shielded twisted pair)
The pair is wrapped with metallic foil or braid to insulate the pair from electromagnetic
interference
• UTP (unshielded twisted pair)
Each wire is insulated with plastic wrap, but the pair is encased in an outer covering

7. COAXIAL CABLE (OR COAX)
• Used for cable television, LANs, telephony
• Has an inner conductor surrounded by a braided mesh
• Both conductors share a common center axial, hence the term “co-axial”
• Coax Advantages:
• Higher bandwidth
• 400 to 600Mhz
• up to 10,800 voice conversations
• Can be tapped easily (pros and cons)
• Much less susceptible to interference than twisted pair
• Coax Disadvantages:
• High attenuation rate makes it expensive over long distance
• Bulky

8. FIBER OPTIC CABLE
• Relatively new transmission medium used by telephone
companies in place of long-distance trunk lines
• Also used by private companies in implementing local data
communications networks
• Require a light source with injection laser diode (ILD) or
light-emitting diodes (LED)
• Fiber Optic Types:
• Multimode step-index fiber
• the reflective walls of the fiber move the light pulses
to the receiver
• Multimode graded-index fiber
• acts to refract the light toward the center of the fiber
by variations in the density
• Single mode fiber
• the light is guided down the center of an extremely
narrow core

9. UNGUIDED OR WIRELESS
TRANSMISSION MEDIA
• Transmission and reception are achieved by means
of an antenna
• Directional
• Transmitting antenna puts out focused beam
• Transmitter and receiver must be aligned
• Omni-Directional
• Signal spreads out in all directions
• Can be received by many antennas
• Wireless Examples :
• Terrestrial Microwave
• Satellite Microwave
• Broadcast Radio
• Infrared

10. TERRESTRIAL
MICROWAVE
• Used for long-distance telephone
service
• Uses radio frequency spectrum,
from 2 to 40 Ghz.
• Parabolic dish transmitter,
mounted high
• Used by common carriers as well
as private networks
• Requires unobstructed line of
sight between source and receiver
• Curvature of the earth requires
stations (repeaters) ~30 miles
apart

11. SATELLITE MICROWAVE
• Television distribution
• Long-distance telephone transmission
• Private business networks
• Satellite Microwave Transmission
• A microwave relay station in space
• Can relay signals over long distances
• Geostationary Satellites
• Remain above the equator at a height of 22,300 miles (geosynchronous orbit)
• T0ravel around the earth in exactly the time the earth takes to rotate
• Satellite Transmission Works
• Earth stations communicate by sending signals to the satellite on an uplink
• The satellite then repeats those signals on a downlink
• The broadcast nature of the downlink makes it attractive for services such as the distribution of
television programming

12. RADIO
• Radio is omnidirectional and
microwave is directional.
• Radio is a general term often used
to encompass frequencies in the
range 3 kHz to 300 GHz.
• Mobile telephony occupies several
frequency bands just under 1 GHz.
• Repeaters need to be placed after
few miles.

13. INFRARED
• Uses transmitters/receivers
(transceivers) that modulate
noncoherent infrared light.
• Transceivers must be within line of
sight of each other (directly or via
reflection ).
• Unlike microwaves, infrared does
not penetrate walls.

14. Thank You
Presented By: Hemant Sarthak